qemu.conf: Clarify the various _tls_x509_cert_dir descriptions
qemu.conf: Clarify the various _tls_x509_cert_dir descriptions

https://bugzilla.redhat.com/show_bug.cgi?id=1458630

Apparantly commit id 'dc4c2f75a' wasn't specific enough, so here's
a few more clarifications.

crobinso/libvirt,jardasgit/libvirt,eskultety/libvirt,jardasgit/libvirt,andreabolognani/libvirt,jfehlig/libvirt,jfehlig/libvirt,olafhering/libvirt,libvirt/libvirt,zippy2/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,nertpinx/libvirt,zippy2/libvirt,fabianfreyer/libvirt,nertpinx/libvirt,crobinso/libvirt,eskultety/libvirt,eskultety/libvirt,zippy2/libvirt,nertpinx/libvirt,nertpinx/libvirt,olafhering/libvirt,olafhering/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,jardasgit/libvirt,jfehlig/libvirt,nertpinx/libvirt,libvirt/libvirt,libvirt/libvirt,andreabolognani/libvirt,zippy2/libvirt,eskultety/libvirt,crobinso/libvirt,crobinso/libvirt,olafhering/libvirt,jardasgit/libvirt,andreabolognani/libvirt,libvirt/libvirt